1 # This file is part of NIT ( http://www.nitlanguage.org ).
3 # Licensed under the Apache License, Version 2.0 (the "License");
4 # you may not use this file except in compliance with the License.
5 # You may obtain a copy of the License at
7 # http://www.apache.org/licenses/LICENSE-2.0
9 # Unless required by applicable law or agreed to in writing, software
10 # distributed under the License is distributed on an "AS IS" BASIS,
11 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 # See the License for the specific language governing permissions and
13 # limitations under the License.
15 # Separate compilation of a Nit program with generic type erasure
16 module separate_erasure_compiler
18 intrude import separate_compiler
20 # Add separate erased compiler specific options
21 redef class ToolContext
23 var opt_erasure
= new OptionBool("Erase generic types", "--erasure")
25 var opt_rta
= new OptionBool("Activate RTA (implicit with --global and --separate)", "--rta")
26 # --no-check-erasure-cast
27 var opt_no_check_erasure_cast
= new OptionBool("Disable implicit casts on unsafe return with erasure-typing policy (dangerous)", "--no-check-erasure-cast")
32 self.option_context
.add_option
(self.opt_erasure
, self.opt_no_check_erasure_cast
, opt_rta
)
35 redef fun process_options
(args
)
39 if opt_no_check_all
.value
then
40 opt_no_check_erasure_cast
.value
= true
44 var erasure_compiler_phase
= new ErasureCompilerPhase(self, null)
47 class ErasureCompilerPhase
49 redef fun process_mainmodule
(mainmodule
, given_mmodules
) do
50 if not toolcontext
.opt_erasure
.value
then return
52 var modelbuilder
= toolcontext
.modelbuilder
54 if toolcontext
.opt_rta
.value
then
55 analysis
= modelbuilder
.do_rapid_type_analysis
(mainmodule
)
57 modelbuilder
.run_separate_erasure_compiler
(mainmodule
, analysis
)
61 redef class ModelBuilder
62 fun run_separate_erasure_compiler
(mainmodule
: MModule, runtime_type_analysis
: nullable RapidTypeAnalysis)
65 self.toolcontext
.info
("*** GENERATING C ***", 1)
67 var compiler
= new SeparateErasureCompiler(mainmodule
, self, runtime_type_analysis
)
68 compiler
.compile_header
70 var c_name
= mainmodule
.c_name
72 # compile class structures
73 self.toolcontext
.info
("Property coloring", 2)
74 compiler
.new_file
("{c_name}.tables")
75 compiler
.do_property_coloring
76 for m
in mainmodule
.in_importation
.greaters
do
77 for mclass
in m
.intro_mclasses
do
78 compiler
.compile_class_to_c
(mclass
)
81 compiler
.compile_color_consts
(compiler
.vt_colors
)
83 # The main function of the C
84 compiler
.new_file
("{c_name}.main")
85 compiler
.compile_nitni_global_ref_functions
86 compiler
.compile_main_function
89 for m
in mainmodule
.in_importation
.greaters
do
90 self.toolcontext
.info
("Generate C for module {m.full_name}", 2)
91 compiler
.new_file
("{m.c_name}.sep")
92 compiler
.compile_module_to_c
(m
)
95 compiler
.display_stats
98 self.toolcontext
.info
("*** END GENERATING C: {time1-time0} ***", 2)
99 write_and_make
(compiler
)
103 class SeparateErasureCompiler
104 super SeparateCompiler
106 private var class_ids
: Map[MClass, Int] is noinit
107 private var class_colors
: Map[MClass, Int] is noinit
108 protected var vt_colors
: Map[MVirtualTypeProp, Int] is noinit
113 var poset
= mainmodule
.flatten_mclass_hierarchy
114 var mclasses
= new HashSet[MClass].from
(poset
)
115 var colorer
= new POSetColorer[MClass]
116 colorer
.colorize
(poset
)
117 class_ids
= colorer
.ids
118 class_colors
= colorer
.colors
119 class_tables
= self.build_class_typing_tables
(mclasses
)
121 # lookup vt to build layout with
122 var vts
= new HashMap[MClass, Set[MVirtualTypeProp]]
123 for mclass
in mclasses
do
124 vts
[mclass
] = new HashSet[MVirtualTypeProp]
125 for mprop
in self.mainmodule
.properties
(mclass
) do
126 if mprop
isa MVirtualTypeProp then
127 vts
[mclass
].add
(mprop
)
133 var vt_colorer
= new POSetBucketsColorer[MClass, MVirtualTypeProp](poset
, colorer
.conflicts
)
134 vt_colors
= vt_colorer
.colorize
(vts
)
135 vt_tables
= build_vt_tables
(mclasses
)
138 fun build_vt_tables
(mclasses
: Set[MClass]): Map[MClass, Array[nullable MPropDef]] do
139 var tables
= new HashMap[MClass, Array[nullable MPropDef]]
140 for mclass
in mclasses
do
141 var table
= new Array[nullable MPropDef]
142 # first, fill table from parents by reverse linearization order
143 var parents
= new Array[MClass]
144 if mainmodule
.flatten_mclass_hierarchy
.has
(mclass
) then
145 parents
= mclass
.in_hierarchy
(mainmodule
).greaters
.to_a
146 self.mainmodule
.linearize_mclasses
(parents
)
148 for parent
in parents
do
149 if parent
== mclass
then continue
150 for mproperty
in self.mainmodule
.properties
(parent
) do
151 if not mproperty
isa MVirtualTypeProp then continue
152 var color
= vt_colors
[mproperty
]
153 if table
.length
<= color
then
154 for i
in [table
.length
.. color
[ do
158 for mpropdef
in mproperty
.mpropdefs
do
159 if mpropdef
.mclassdef
.mclass
== parent
then
160 table
[color
] = mpropdef
166 # then override with local properties
167 for mproperty
in self.mainmodule
.properties
(mclass
) do
168 if not mproperty
isa MVirtualTypeProp then continue
169 var color
= vt_colors
[mproperty
]
170 if table
.length
<= color
then
171 for i
in [table
.length
.. color
[ do
175 for mpropdef
in mproperty
.mpropdefs
do
176 if mpropdef
.mclassdef
.mclass
== mclass
then
177 table
[color
] = mpropdef
181 tables
[mclass
] = table
187 fun build_class_typing_tables
(mclasses
: Set[MClass]): Map[MClass, Array[nullable MClass]] do
188 var tables
= new HashMap[MClass, Array[nullable MClass]]
189 for mclass
in mclasses
do
190 var table
= new Array[nullable MClass]
191 var supers
= new Array[MClass]
192 if mainmodule
.flatten_mclass_hierarchy
.has
(mclass
) then
193 supers
= mclass
.in_hierarchy
(mainmodule
).greaters
.to_a
196 var color
= class_colors
[sup
]
197 if table
.length
<= color
then
198 for i
in [table
.length
.. color
[ do
204 tables
[mclass
] = table
209 redef fun compile_header_structs
do
210 self.header
.add_decl
("typedef void(*nitmethod_t)(void); /* general C type representing a Nit method. */")
211 self.compile_header_attribute_structs
212 self.header
.add_decl
("struct class \{ int id; const char *name; int box_kind; int color; const struct vts_table *vts_table; const struct type_table *type_table; nitmethod_t vft[]; \}; /* general C type representing a Nit class. */")
213 self.header
.add_decl
("struct type_table \{ int size; int table[]; \}; /* colorized type table. */")
214 self.header
.add_decl
("struct vts_entry \{ short int is_nullable; const struct class *class; \}; /* link (nullable or not) between the vts and is bound. */")
215 self.header
.add_decl
("struct vts_table \{ int dummy; const struct vts_entry vts[]; \}; /* vts list of a C type representation. */")
216 self.header
.add_decl
("typedef struct instance \{ const struct class *class; nitattribute_t attrs[1]; \} val; /* general C type representing a Nit instance. */")
219 redef fun compile_class_to_c
(mclass
: MClass)
221 var mtype
= mclass
.intro
.bound_mtype
222 var c_name
= mclass
.c_name
224 var vft
= self.method_tables
[mclass
]
225 var attrs
= self.attr_tables
[mclass
]
226 var class_table
= self.class_tables
[mclass
]
227 var v
= self.new_visitor
229 var rta
= runtime_type_analysis
230 var is_dead
= false # mclass.kind == abstract_kind or mclass.kind == interface_kind
231 if not is_dead
and rta
!= null and not rta
.live_classes
.has
(mclass
) and mtype
.ctype
== "val*" and mclass
.name
!= "NativeArray" then
235 v
.add_decl
("/* runtime class {c_name} */")
237 self.provide_declaration
("class_{c_name}", "extern const struct class class_{c_name};")
238 v
.add_decl
("extern const struct type_table type_table_{c_name};")
241 v
.add_decl
("const struct class class_{c_name} = \{")
242 v
.add_decl
("{class_ids[mclass]},")
243 v
.add_decl
("\"{mclass.name}\
", /* class_name_string */")
244 v
.add_decl
("{self.box_kind_of(mclass)}, /* box_kind */")
245 v
.add_decl
("{class_colors[mclass]},")
247 if build_class_vts_table
(mclass
) then
248 v
.require_declaration
("vts_table_{c_name}")
249 v
.add_decl
("&vts_table_{c_name},")
253 v
.add_decl
("&type_table_{c_name},")
255 for i
in [0 .. vft
.length
[ do
256 var mpropdef
= vft
[i
]
257 if mpropdef
== null then
258 v
.add_decl
("NULL, /* empty */")
260 assert mpropdef
isa MMethodDef
261 if rta
!= null and not rta
.live_methoddefs
.has
(mpropdef
) then
262 v
.add_decl
("NULL, /* DEAD {mclass.intro_mmodule}:{mclass}:{mpropdef} */")
265 if true or mpropdef
.mclassdef
.bound_mtype
.ctype
!= "val*" then
266 v
.require_declaration
("VIRTUAL_{mpropdef.c_name}")
267 v
.add_decl
("(nitmethod_t)VIRTUAL_{mpropdef.c_name}, /* pointer to {mclass.intro_mmodule}:{mclass}:{mpropdef} */")
269 v
.require_declaration
("{mpropdef.c_name}")
270 v
.add_decl
("(nitmethod_t){mpropdef.c_name}, /* pointer to {mclass.intro_mmodule}:{mclass}:{mpropdef} */")
278 # Build class type table
280 v
.add_decl
("const struct type_table type_table_{c_name} = \{")
281 v
.add_decl
("{class_table.length},")
283 for msuper
in class_table
do
284 if msuper
== null then
285 v
.add_decl
("-1, /* empty */")
287 v
.add_decl
("{self.class_ids[msuper]}, /* {msuper} */")
293 if mtype
.ctype
!= "val*" or mtype
.mclass
.name
== "Pointer" then
294 #Build instance struct
295 self.header
.add_decl
("struct instance_{c_name} \{")
296 self.header
.add_decl
("const struct class *class;")
297 self.header
.add_decl
("{mtype.ctype} value;")
298 self.header
.add_decl
("\};")
301 self.provide_declaration
("BOX_{c_name}", "val* BOX_{c_name}({mtype.ctype});")
302 v
.add_decl
("/* allocate {mtype} */")
303 v
.add_decl
("val* BOX_{mtype.c_name}({mtype.ctype} value) \{")
304 v
.add
("struct instance_{c_name}*res = nit_alloc(sizeof(struct instance_{c_name}));")
305 v
.require_declaration
("class_{c_name}")
306 v
.add
("res->class = &class_{c_name};")
307 v
.add
("res->value = value;")
308 v
.add
("return (val*)res;")
311 if mtype
.mclass
.name
!= "Pointer" then return
314 self.provide_declaration
("NEW_{c_name}", "{mtype.ctype} NEW_{c_name}();")
315 v
.add_decl
("/* allocate {mtype} */")
316 v
.add_decl
("{mtype.ctype} NEW_{c_name}() \{")
318 v
.add_abort
("{mclass} is DEAD")
320 var res
= v
.new_named_var
(mtype
, "self")
322 v
.add
("{res} = nit_alloc(sizeof(struct instance_{mtype.c_name}));")
323 v
.require_declaration
("class_{c_name}")
324 v
.add
("{res}->class = &class_{c_name};")
325 v
.add
("((struct instance_{mtype.c_name}*){res})->value = NULL;")
326 v
.add
("return {res};")
330 else if mclass
.name
== "NativeArray" then
331 #Build instance struct
332 self.header
.add_decl
("struct instance_{c_name} \{")
333 self.header
.add_decl
("const struct class *class;")
334 self.header
.add_decl
("int length;")
335 self.header
.add_decl
("val* values[];")
336 self.header
.add_decl
("\};")
339 self.provide_declaration
("NEW_{c_name}", "{mtype.ctype} NEW_{c_name}(int length);")
340 v
.add_decl
("/* allocate {mtype} */")
341 v
.add_decl
("{mtype.ctype} NEW_{c_name}(int length) \{")
342 var res
= v
.get_name
("self")
343 v
.add_decl
("struct instance_{c_name} *{res};")
344 var mtype_elt
= mtype
.arguments
.first
345 v
.add
("{res} = nit_alloc(sizeof(struct instance_{c_name}) + length*sizeof({mtype_elt.ctype}));")
346 v
.require_declaration
("class_{c_name}")
347 v
.add
("{res}->class = &class_{c_name};")
348 v
.add
("{res}->length = length;")
349 v
.add
("return (val*){res};")
352 else if mtype
.mclass
.kind
== extern_kind
and mtype
.mclass
.name
!= "NativeString" then
353 var pointer_type
= mainmodule
.pointer_type
355 self.provide_declaration
("NEW_{c_name}", "{mtype.ctype} NEW_{c_name}();")
356 v
.add_decl
("/* allocate {mtype} */")
357 v
.add_decl
("{mtype.ctype} NEW_{c_name}() \{")
359 v
.add_abort
("{mclass} is DEAD")
361 var res
= v
.new_named_var
(mtype
, "self")
363 v
.add
("{res} = nit_alloc(sizeof(struct instance_{pointer_type.c_name}));")
364 #v.add("{res}->type = type;")
365 v
.require_declaration
("class_{c_name}")
366 v
.add
("{res}->class = &class_{c_name};")
367 v
.add
("((struct instance_{pointer_type.c_name}*){res})->value = NULL;")
368 v
.add
("return {res};")
375 self.provide_declaration
("NEW_{c_name}", "{mtype.ctype} NEW_{c_name}(void);")
376 v
.add_decl
("/* allocate {mtype} */")
377 v
.add_decl
("{mtype.ctype} NEW_{c_name}(void) \{")
379 v
.add_abort
("{mclass} is DEAD")
382 var res
= v
.new_named_var
(mtype
, "self")
384 v
.add
("{res} = nit_alloc(sizeof(struct instance) + {attrs.length}*sizeof(nitattribute_t));")
385 v
.require_declaration
("class_{c_name}")
386 v
.add
("{res}->class = &class_{c_name};")
387 self.generate_init_attr
(v
, res
, mtype
)
389 v
.add
("return {res};")
394 private fun build_class_vts_table
(mclass
: MClass): Bool do
395 if self.vt_tables
[mclass
].is_empty
then return false
397 self.provide_declaration
("vts_table_{mclass.c_name}", "extern const struct vts_table vts_table_{mclass.c_name};")
400 v
.add_decl
("const struct vts_table vts_table_{mclass.c_name} = \{")
401 v
.add_decl
("0, /* dummy */")
404 for vt
in self.vt_tables
[mclass
] do
406 v
.add_decl
("\{-1, NULL\}, /* empty */")
409 var bound
= retrieve_vt_bound
(mclass
.intro
.bound_mtype
, vt
.as(MVirtualTypeDef).bound
)
410 while bound
isa MNullableType do
411 bound
= retrieve_vt_bound
(mclass
.intro
.bound_mtype
, bound
.mtype
)
414 var vtclass
= bound
.as(MClassType).mclass
415 v
.require_declaration
("class_{vtclass.c_name}")
416 v
.add_decl
("\{{is_null}, &class_{vtclass.c_name}\}, /* {vt} */")
424 private fun retrieve_vt_bound
(anchor
: MClassType, mtype
: nullable MType): MType do
425 if mtype
== null then
426 print
"NOT YET IMPLEMENTED: retrieve_vt_bound on null"
429 if mtype
isa MVirtualType then
430 return mtype
.anchor_to
(mainmodule
, anchor
)
431 else if mtype
isa MParameterType then
432 return mtype
.anchor_to
(mainmodule
, anchor
)
438 redef fun new_visitor
do return new SeparateErasureCompilerVisitor(self)
442 private var class_tables
: Map[MClass, Array[nullable MClass]] is noinit
443 private var vt_tables
: Map[MClass, Array[nullable MPropDef]] is noinit
445 redef fun display_sizes
447 print
"# size of subtyping tables"
448 print
"\ttotal \tholes"
451 for t
, table
in class_tables
do
452 total
+= table
.length
453 for e
in table
do if e
== null then holes
+= 1
455 print
"\t{total}\t{holes}"
457 print
"# size of resolution tables"
458 print
"\ttotal \tholes"
461 for t
, table
in vt_tables
do
462 total
+= table
.length
463 for e
in table
do if e
== null then holes
+= 1
465 print
"\t{total}\t{holes}"
467 print
"# size of methods tables"
468 print
"\ttotal \tholes"
471 for t
, table
in method_tables
do
472 total
+= table
.length
473 for e
in table
do if e
== null then holes
+= 1
475 print
"\t{total}\t{holes}"
477 print
"# size of attributes tables"
478 print
"\ttotal \tholes"
481 for t
, table
in attr_tables
do
482 total
+= table
.length
483 for e
in table
do if e
== null then holes
+= 1
485 print
"\t{total}\t{holes}"
489 class SeparateErasureCompilerVisitor
490 super SeparateCompilerVisitor
492 redef fun compile_callsite
(callsite
, arguments
)
495 if callsite
.erasure_cast
and not self.compiler
.as(SeparateErasureCompiler).modelbuilder
.toolcontext
.opt_no_check_erasure_cast
.value
then
497 var mtype
= callsite
.msignature
.return_mtype
499 self.add
("/* Erasure cast for return {res} isa {mtype} */")
500 var cond
= self.type_test
(res
, mtype
, "erasure")
501 self.add
("if (!{cond}) \{")
502 #var x = self.class_name_string(res)
503 #var y = self.class_name_string(arguments.first)
504 #self.add("PRINT_ERROR(\"Erasure cast: expected {mtype} (self is %s), got %s for {res}\\n\", {y}, {x});")
505 self.add_abort
("Cast failed")
511 redef fun init_instance
(mtype
)
513 self.require_declaration
("NEW_{mtype.mclass.c_name}")
514 return self.new_expr
("NEW_{mtype.mclass.c_name}()", mtype
)
517 redef fun type_test
(value
, mtype
, tag
)
519 self.add
("/* type test for {value.inspect} isa {mtype} */")
521 var res
= self.new_var
(bool_type
)
523 var cltype
= self.get_name
("cltype")
524 self.add_decl
("int {cltype};")
525 var idtype
= self.get_name
("idtype")
526 self.add_decl
("int {idtype};")
528 var maybe_null
= self.maybe_null
(value
)
529 var accept_null
= "0"
530 if mtype
isa MNullableType then
534 if mtype
isa MParameterType then
535 # Here we get the bound of the the formal type (eh, erasure...)
536 mtype
= mtype
.resolve_for
(self.frame
.mpropdef
.mclassdef
.bound_mtype
, self.frame
.mpropdef
.mclassdef
.bound_mtype
, self.frame
.mpropdef
.mclassdef
.mmodule
, false)
537 if mtype
isa MNullableType then
543 if value
.mcasttype
.is_subtype
(self.frame
.mpropdef
.mclassdef
.mmodule
, self.frame
.mpropdef
.mclassdef
.bound_mtype
, mtype
) then
544 self.add
("{res} = 1; /* easy {value.inspect} isa {mtype}*/")
545 if compiler
.modelbuilder
.toolcontext
.opt_typing_test_metrics
.value
then
546 self.compiler
.count_type_test_skipped
[tag
] += 1
547 self.add
("count_type_test_skipped_{tag}++;")
553 if value
.mtype
.ctype
== "val*" then
554 class_ptr
= "{value}->class->"
556 var mclass
= value
.mtype
.as(MClassType).mclass
557 self.require_declaration
("class_{mclass.c_name}")
558 class_ptr
= "class_{mclass.c_name}."
561 if mtype
isa MClassType then
562 self.require_declaration
("class_{mtype.mclass.c_name}")
563 self.add
("{cltype} = class_{mtype.mclass.c_name}.color;")
564 self.add
("{idtype} = class_{mtype.mclass.c_name}.id;")
565 if compiler
.modelbuilder
.toolcontext
.opt_typing_test_metrics
.value
then
566 self.compiler
.count_type_test_resolved
[tag
] += 1
567 self.add
("count_type_test_resolved_{tag}++;")
569 else if mtype
isa MVirtualType then
570 var recv
= self.frame
.arguments
.first
572 if recv
.mtype
.ctype
== "val*" then
573 recv_ptr
= "{recv}->class->"
575 var mclass
= recv
.mtype
.as(MClassType).mclass
576 self.require_declaration
("class_{mclass.c_name}")
577 recv_ptr
= "class_{mclass.c_name}."
579 var entry
= self.get_name
("entry")
580 self.add
("struct vts_entry {entry};")
581 self.require_declaration
(mtype
.mproperty
.const_color
)
582 self.add
("{entry} = {recv_ptr}vts_table->vts[{mtype.mproperty.const_color}];")
583 self.add
("{cltype} = {entry}.class->color;")
584 self.add
("{idtype} = {entry}.class->id;")
585 if maybe_null
and accept_null
== "0" then
586 var is_nullable
= self.get_name
("is_nullable")
587 self.add_decl
("short int {is_nullable};")
588 self.add
("{is_nullable} = {entry}.is_nullable;")
589 accept_null
= is_nullable
.to_s
591 if compiler
.modelbuilder
.toolcontext
.opt_typing_test_metrics
.value
then
592 self.compiler
.count_type_test_unresolved
[tag
] += 1
593 self.add
("count_type_test_unresolved_{tag}++;")
596 self.debug
("type_test({value.inspect}, {mtype})")
600 # check color is in table
602 self.add
("if({value} == NULL) \{")
603 self.add
("{res} = {accept_null};")
604 self.add
("\} else \{")
606 self.add
("if({cltype} >= {class_ptr}type_table->size) \{")
607 self.add
("{res} = 0;")
608 self.add
("\} else \{")
609 self.add
("{res} = {class_ptr}type_table->table[{cltype}] == {idtype};")
618 redef fun unbox_extern
(value
, mtype
)
620 if mtype
isa MClassType and mtype
.mclass
.kind
== extern_kind
and
621 mtype
.mclass
.name
!= "NativeString" then
622 var pointer_type
= compiler
.mainmodule
.pointer_type
623 var res
= self.new_var_extern
(mtype
)
624 self.add
"{res} = ((struct instance_{pointer_type.c_name}*){value})->value; /* unboxing {value.mtype} */"
631 redef fun box_extern
(value
, mtype
)
633 if mtype
isa MClassType and mtype
.mclass
.kind
== extern_kind
and
634 mtype
.mclass
.name
!= "NativeString" then
635 var valtype
= compiler
.mainmodule
.pointer_type
636 var res
= self.new_var
(mtype
)
637 if compiler
.runtime_type_analysis
!= null and not compiler
.runtime_type_analysis
.live_types
.has
(value
.mtype
.as(MClassType)) then
638 self.add
("/*no boxing of {value.mtype}: {value.mtype} is not live! */")
639 self.add
("PRINT_ERROR(\"Dead code executed
!\\n\
"); show_backtrace(1);")
642 self.require_declaration
("BOX_{valtype.c_name}")
643 self.add
("{res} = BOX_{valtype.c_name}({value}); /* boxing {value.mtype} */")
644 self.require_declaration
("class_{mtype.c_name}")
645 self.add
("{res}->class = &class_{mtype.c_name};")
652 redef fun class_name_string
(value
)
654 var res
= self.get_name
("var_class_name")
655 self.add_decl
("const char* {res};")
656 if value
.mtype
.ctype
== "val*" then
657 self.add
"{res} = {value} == NULL ? \"null\
" : {value}->class->name;"
659 self.require_declaration
("class_{value.mtype.c_name}")
660 self.add
"{res} = class_{value.mtype.c_name}.name;"
665 redef fun native_array_instance
(elttype
, length
)
667 var nclass
= self.get_class
("NativeArray")
668 var mtype
= nclass
.get_mtype
([elttype
])
669 var res
= self.new_var
(mtype
)
671 self.require_declaration
("NEW_{nclass.c_name}")
672 self.add
("{res} = NEW_{nclass.c_name}({length});")
676 redef fun calloc_array
(ret_type
, arguments
)
678 var ret
= ret_type
.as(MClassType)
679 self.require_declaration
("NEW_{ret.mclass.c_name}")
680 self.ret
(self.new_expr
("NEW_{ret.mclass.c_name}({arguments[1]})", ret_type
))